For a very long time mkgmap (the program to render Garmin maps based on OSM) development had stalled and there have been no major improvements. Last week though quite a few improvements got pushed trough and a lot of work was done. The major and most important has been, that the Multipolygon support when cooinciding the relations has been improved a lot (or better said is working near to 100% correct now).

The importance of this is around 0.5% bigger maps in well mapped countries - meaning quite a few areas that were previously missing are now rendered correctly. On the other hand the feature missing most, correct address search has still not improved, and I don't think it will until Stan from cgpsmapper releases cgpsmapper sourcecode - which however happen soon, as he announced to maybe opensource cgpsmapper in 4/4 2010 or otherwise offer cgpsmapper pro for free (which in return would make revererse engineering the last mistakes of the Garmin format implementation easier, and hopefully also lead to a fully working address search).